Huda Walter, Tipnis Sameer V
Department of Radiology and Radiological Science, MUSC, 96 Jonathan Lucas St, MSC 323, Charleston, SC 29425-3230, USA.
Department of Radiology and Radiological Science, MUSC, 96 Jonathan Lucas St, MSC 323, Charleston, SC 29425-3230, USA
Radiat Prot Dosimetry. 2016 Mar;168(3):374-80. doi: 10.1093/rpd/ncv310. Epub 2015 May 13.
The aim of this study was to investigate how effective dose and size-specific dose estimate (SSDE) change with patient age (size) for routine head and abdominal/pelvic CT examinations. Heads and abdomens of patients were modelled as a mass-equivalent cylinder of water corresponding to the patient 'effective diameter'. Head CT scans were performed at CTDIvol(S) of 40 mGy, and abdominal CT scans were performed at CTDIvol(L) of 10 mGy. Values of SSDE were obtained using conversion factors in AAPM Task Group Report 204. Age-specific scan lengths for head and abdominal CT scans obtained from the authors' clinical practice were used to estimate the dose-length product for each CT examination. Effective doses were calculated from previously published age- and sex-specific E/DLP conversion factors, based on ICRP 103 organ-weighting factors. For head CT examinations, the scan length increased from 15 cm in a newborn to 20 cm in adults, and for an abdominal/pelvic CT, the scan length increased from 20 cm in a newborn to 45 cm in adults. For head CT scans, SSDE ranged from 37.2 mGy in adults to 48.8 mGy in a newborn, an increase of 31 %. The corresponding head CT effective doses range from 1.4 mSv in adults to 5.2 mSv in a newborn, an increase of 270 %. For abdomen CT scans, SSDE ranged from 13.7 mGy in adults to 23.0 mGy in a newborn, an increase of 68 %. The corresponding abdominal CT effective doses ranged from 6.3 mSv in adults to 15.4 mSv in a newborn, an increase of 140 %. SSDE increases much less than effective dose in paediatric patients compared with adults because it does not account for scan length or scattered radiation. Size- and age-specific effective doses better quantify the total radiation received by patients in CT by explicitly accounting for all organ doses, as well as their relative radio sensitivity.
本研究的目的是调查在常规头部和腹部/盆腔CT检查中，有效剂量和大小特异性剂量估计值（SSDE）如何随患者年龄（体型）变化。将患者的头部和腹部建模为与患者“有效直径”对应的水的质量等效圆柱体。头部CT扫描在CTDIvol(S)为40 mGy时进行，腹部CT扫描在CTDIvol(L)为10 mGy时进行。使用AAPM任务组报告204中的转换因子获得SSDE值。从作者的临床实践中获得的头部和腹部CT扫描的特定年龄扫描长度用于估计每次CT检查的剂量长度乘积。有效剂量根据先前发表的基于ICRP 103器官加权因子的年龄和性别特异性E/DLP转换因子计算。对于头部CT检查，扫描长度从新生儿的15 cm增加到成人的20 cm，对于腹部/盆腔CT，扫描长度从新生儿的20 cm增加到成人的45 cm。对于头部CT扫描，SSDE范围从成人的37.2 mGy到新生儿的48.8 mGy，增加了31%。相应的头部CT有效剂量范围从成人的1.4 mSv到新生儿的5.2 mSv，增加了270%。对于腹部CT扫描，SSDE范围从成人的13.7 mGy到新生儿的23.0 mGy，增加了68%。相应的腹部CT有效剂量范围从成人的6.3 mSv到新生儿的15.4 mSv，增加了140%。与成人相比，儿科患者的SSDE增加远小于有效剂量，因为它没有考虑扫描长度或散射辐射。特定大小和年龄的有效剂量通过明确考虑所有器官剂量及其相对辐射敏感性，能更好地量化患者在CT检查中接受的总辐射量。
